At least 31 residents in an east China county have been found to have elevated levels of lead in their blood as investigators probe a local battery plant suspected of leaking the element, local officials said Monday.

Police in Deqing County, Zhejiang Province, are also questioning the head of the local battery plant suspected of leaking the lead, a spokesman for the county government said.

Operations of the Zhejiang Haijiu Battery Co., Ltd. remain suspended.

Meanwhile, a team of investigators with the Ministry of Environmental Protection have joined the probe.

The spokesman said 317 villagers have been administered blood tests. Thirty-one, including eleven children, were found to have excessive amounts of lead in their blood. More than 1,600 others are awaiting their test results.

Excessive amounts of lead in the blood can damage the digestive, nervous, and reproductive systems and cause stomach aches, anemia and convulsions.

Authorities have ordered a safety check of all 26 heavy metal factories in Deqing.

Haijiu Battery Co., Ltd., founded in May, 2003, mainly produces lead-acid batteries for motorcycles. It has about 1,000 employees and an annual output of 9 million batteries.